Revert "Clang changes to support LLVM removal of runtime multithreading"

This reverts r210601.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210604 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 5 deletions

diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 7320bbd085..4d296d46b7 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -2556,8 +2556,8 @@ buildPieces(unsigned NameFlags, bool IsMemberRefExpr,
 // Misc. API hooks.
 //===----------------------------------------------------------------------===//               
 
-static llvm::sys::Mutex LoggingMutex;
-static std::once_flag InstalledErrorHandlerFlag;
+static llvm::sys::Mutex EnableMultithreadingMutex;
+static bool EnabledMultithreading;
 
 static void fatal_error_handler(void *user_data, const std::string& reason,
                                 bool gen_crash_diag) {
@@ -2575,8 +2575,15 @@ CXIndex clang_createIndex(int excludeDeclarationsFromPCH,
   if (!getenv("LIBCLANG_DISABLE_CRASH_RECOVERY"))
     llvm::CrashRecoveryContext::Enable();
 
-  std::call_once(InstalledErrorHandlerFlag,
-      []() {llvm::install_fatal_error_handler(fatal_error_handler, nullptr);});
+  // Enable support for multithreading in LLVM.
+  {
+    llvm::sys::ScopedLock L(EnableMultithreadingMutex);
+    if (!EnabledMultithreading) {
+      llvm::install_fatal_error_handler(fatal_error_handler, nullptr);
+      llvm::llvm_start_multithreaded();
+      EnabledMultithreading = true;
+    }
+  }
 
   CIndexer *CIdxr = new CIndexer();
   if (excludeDeclarationsFromPCH)
@@ -6952,7 +6959,7 @@ Logger &cxindex::Logger::operator<<(const llvm::format_object_base &Fmt) {
 cxindex::Logger::~Logger() {
   LogOS.flush();
 
-  llvm::sys::ScopedLock L(LoggingMutex);
+  llvm::sys::ScopedLock L(EnableMultithreadingMutex);
 
   static llvm::TimeRecord sBeginTR = llvm::TimeRecord::getCurrentTime();